Typewriter key guide



March Z5, 1941. F. PIRNAT Erm.. 2,236,413

TYPEWRITER KEY GUIDE Filed Dec. 1939 {7j/3 2. A1m /'7 /9 25 zedqmm @f @Q Wl l 9282/27 III QJJQLJ) JJ'JJJJJ) Q INVENTOR ATTORNEYS l Patented Mar. 25, 1941 rrrnwmran. Knr GUIDE l Application December 26, 1939, Serial No. 3i0,990

'2 claims. (Cl. 19t- 107) UNITED STATES PATENT OFFICE This invention relates to typewriter key guides angular ends I S which terminate in ring bearand has for an object Ito provide a device of this character adapted to eliminate jamming of the key levers by allowing only one key to be dev pressed at a time so that it is possible to get more speed and accuracy in typing as the typist does not lose position or get distracted by reaching over to disentangle the type levers.

A further object is to provide a device of this character having `a novel adjusting bar adapted to maintain the proper clearance which is the thickness of one key lever, so that only one key lever may go between the steel balls of the device at a time.

A further object is to provide a device of this character which will be formed of a few strong simple and durable parts, lwhich will be inex-I pensive to manufacture, and which will not easily get out of order. l

With the above and other objects in view the invention consists of certain novel details of construction and combinations .of parts hereinafter fully described and claimed, it being understood that various modications may be resorted to within the scope of the appended claims without departing from the spirit or sacriiicingany of the advantages of the invention.

In the accompanying drawing forming a part of this specification:

Figure l is a longitudinal sectional view of a typewriter key' guide constructed in accordance with the invention and showing all of the key levers raised.

Figure 2 is a longitudinal sectional view of the key guide showing one of thelevers depressed.

Figure 3 is a cross sectional view of the device.

Figure 4 is a detail perspective view of the adjusting bar.

Referring now to Ithe drawing in which like characters of reference designate similar parts in the various views, I designates a frame bar which underlies and extends transversely of the key levers II of a typewriter. The irame bar is provided with a ball channel I2 which extends longitudinally thereof and the bar is also provided with vertical slots I3 which intersect the ballchannel. In the upper portion of .the slots the key levers I I' normally rest.

The frame bar I0 is provided below the ball channel I2 and key slots I3 with a longitudinal the frame bar. As best shown in Figure 4. the adjusting bar is provided with upwardly directed tion. guide slot It in which an adjusting bar I5 is 'l mounted for endwise movementl with relation to.

ings I'l which are internally threaded.

Adjusting screws I8 and I9 are threadedly engaged in respective ring bearings and extend into respective openings and 2| formed in the ends 5 f the bar l0, which openings communicate with the ball channel I2. The adjusting screws are held against accidental movement with relation to the adjusting bar by respective lock nuts 22 and 23. One end of the ball channel is bored to 10' provide a stop shoulder 24. for contact with the adjusting screw I8 tting in said end of the channel.V Y

A coil spring 25 is sleeved on the stem of a plunger 26 which is received in a bore 21 of the 15` adjusting screw I9. A coil spring 28 is sleeved on the adjusting screw I9 between the respective ring bearing I1 and the adjacent end of the frame bar IG. v

A plurality of balls 29 are disposed in .theball 2 0 channel I2 and are normally held in engagement with each other, and the terminal balls of the row are held in engagement with the adjusting screw I8 and plunger 26, by the coaction of the springs 25 and 28. These springs tend normally 25 to hold the adjusting screw Ill against the stop shoulder 2d by sliding the adjusting bar endwise but yield sufiiciently when one of the key levers I I is depressed to permit that particular key lever to pass into the respective key slot. I3 between 30 land below a pair of balls, by displacing the balls on each side of the key lever a distance equal to only one-half the thickness of the key, lever as best shown in Figure 2. At this time no two key levers can pass-'between the balls due to the ad- 35 justment of the screws being such that the-clearance between any two balls when one of the key levers is disposed between them is exactly the same as the thickness of the key lever and thus Vall the rest of the balls are disposed in abutting 40 engagement with each other from end to end of the ball channel and prevent any other key lever being depressed.

It will be understood that the key guide above described may be used on other machines having a plurality of key levers and is not confined only` to'typewriters.

From the above description it is thought that the construction and opration of the invention will be fully understood without further explana- What is claimed is: v

l. The combination with the frame and thev key levers oa machine, of a frame bar connectedto the frame and underlying y and extending transversely of the key levers, the frame bar being provided with a ball channel extending longitudinally thereof, a series of balls in contact with each other from end to end of said channel, the frame bar being provided with vertical slots intersecting the ball channel and in the upper por,- tion of which the key levers normally rest, the frame bar being provided below the ball channel with a longitudinal guide opening, an adjusting bar slidably mounted for endwise movement in the guide opening and having upwardly directed ends spaced from the frame bar, adjusting screws carried by said ends extending into the ends of the ball channel, one end of the ball channel being counter-bored to provide a stop shoulder` for contact with the adjusting screw tting in said end of the channel, a helical spring sleeved on the other adjusting screw between the frame bar and the upwardly directed end of the adjusting bar carrying said screw, yielding means on the last-named adjusting screw normally holding said vballs in contact with each other, said hellcal spring constantly tending justing bar endwise to hold the rst-named adjusting screw against said stop shoulder, said helical spring and said yielding means 'permitting the balls on each side of a key lever to be displaced by depression of said key lever only a distance equal to one-half the width of the key lever while all the other balls are disposed in abutting engagement with each other from end to end of the ball channel to prevent more than one key lever at a time being depressed.

2. The structure as recited in claim 1 in which said yielding means consists of a spring-pressed plunger carried by the associated adjusting screw engaging the adjacent ball of the series of balls.

FRED PIRNAT. PHILIP PIRNAT.

to move the ad- 

